1. Field of the Invention
The present invention relates to dishwashing appliances and more particularly to a liquid distribution system for a spray device within such an appliance.
2. Prior Art
Dishwashing appliances which have a rotatable spray device located above a dish-supporting rack and which include a liquid distribution system for directing liquid from a pressurized liquid source to the spray device for distribution of wash liquid over dishes, pots, pans, etc., placed in a supporting rack within the washing chamber of the appliance are known.
Some of such appliances include an upper and lower dish-supporting rack which are separably movable into and out of the washing chamber of the appliance for the loading and unloading of dishes, etc. Each dish-supporting rack is generally located adjacent at least one spray device, and positioned so as not to interfere with rack movement. A liquid distribution system provides wash liquid to each of the spray devices which are generally of the reaction type, that is, caused to rotate by the reaction force of pressurized wash liquid exiting through apertures therein. U.S. Pat. Nos. 3,009,470 and 3,064,664 both disclose an appliance such as just described, with a liquid distribution system which, at least during operation, forms a unitary structure with upper and lower spray devices. Fluid pressure in the associated water distribution system is required to rotate both spray devices. Even with relatively lightweight materials, such as sheet metal or plastic, such an overall unitary structure has considerable mass and therefore requires relatively large expenditures of fluid pressure which is then not available for scouring and otherwise washing the dishes, etc., within the appliance. Further, unitary rotatable liquid distribution systems are relatively complex to manufacture and install and are also difficult to service and maintain in proper working order, rendering appliances containing such systems uneconomic.
U.S. Pat. No. 3,370,869, issued to I. G. Dutcher on Feb. 27, 1968 and assigned to the assignee of the present invention, discloses and claims a partial solution to the above-noted drawbacks in certain dishwashing appliances. As shown therein, a spray device can be inexpensively mounted for rotation on a fixed-hub fluid distribution system, at least in instances where there is no requirement for periodic separation of the spray device from its associated liquid distribution system, such as required when the spray device is located above a dish-supporting rack and must be separated from its liquid distribution system to permit movement of this lower rack from the washing chamber for loading or unloading dishes, etc.
U.S. Pat. No. 3,785,566, issued to Thomas E. Jenkins on Jan. 15, 1974, discloses an example of the use of an expanding seal member to provide a fluid passageway joining the pump outlet and a lower spray device in a dishwashing appliance.